Onion (Allium cepa L.) is among the most important food plants with high nutritional value, but insufficient application of phosphorous is one of the constraints to the yields. Research on onion responses to different doses of phosphorus will optimize fertilizer dose, making the practice more competitive with less environmental effects. Three field experiments were carried out fortwo years to evaluate the effect of different phosphorus levels on the yield of onion in Randomized Complete Block Design (RCBD) with three replications and four treatments (80, 120, 160, and 200 Kg P2O5 ha-1 ) along with N and K at a rate of 60 Kg ha-1 . From the results, it can be concluded that the onion responded to applied phosphorus doses and the variance analysis showed that the P effect was significant. The maximum (18.58 t ha-1 ) onion bulb yield was obtained from a combination of NPK @60-200-60 Kg ha-1 and was appeared statistically equal to the yield (18.41 t ha-1 ) obtained from NPK @ 60-160-60 Kg ha-1 which also found suitable, effective and economically viable for the cultivation of onions in Punjab, Pakistan.